The catalytic oxidation of toluene can produce benzaldehyde and benzoic acid. See, for example, Daniel, U.S. Pat. No. 4,390,728 (1983); Chem. Abs., 97(15):126,725m, abstracting Madhock et al., Indian J. Technol., 20(5), 184-89 (1982); Andersson, J. Catal., 98, 138 (1986).
Anthraquinone has been allegedly prepared by the use of diluted toluene in air (1.2 percent). See, for example, Japan Kokai Nos. 1982-24323 and 1983-121238. Such known processes to prepare anthraquinone by direct toluene oxidation can be generally inefficient. Loss of valuable reactant materials through complete combustion to carbon dioxide can be particularly problematical.